When your alarm clock doesn't go off, you can thank a humble enzyme for getting you out of bed, scientists at the Salk Institute reveal in research published today.

Researchers examining the mechanisms that control our sleep have found the chemical reaction that makes us stir abruptly, throw the cat off the bed and stumble blinking into the bathroom.

They have pinpointed an enzyme called JARID1a which acts as a molecular "bugle call" to our cells, firing them into action, say research team led by Satchindananda Panda and Luciano DiTacchio.

We've already known that a protein called PERIOD or PER is at the centre of our biological clock – raising blood pressure, stimulating heart rate and mental processes – but what shuts it down at night or gets it going again in the morning was unclear.

Tests with human cells and fruit flies suggest that JARID1a is vital to healthy sleep patterns, and that it ensures that the PER protein rises to its normal peak each day.

Fruit flies that were genetically modified to under-produce JARID1a lost their circadian rhythms completely: "Flies deprived of JARID1a took frequent naps and were unable to settle into a normal pattern of sleeping," the researchers reported.

Our body clock is vital in regulating a whole range of functions – and any malfunctioning in the genes which control these processes can result in various disorders. Scientists hope their research will be useful in helping with investigations into those diseases.